1. Field of the Invention
The present invention pertains to the art of refrigerators and, more particularly, to a sensor system employed in a dispenser mounted in a refrigerator door.
2. Description of the Related Art
Refrigerators having built-in ice/water dispensers are well known in the art. In general, the dispensers are mounted to a door of the refrigerator for the purpose of dispensing ice and/or water without requiring a user to access a refrigerator compartment. A typical dispenser includes a dispenser well into which a container is placed. Once the container is in position, an actuator is operated to release the ice and/or water into the container.
In many cases, the actuator is a pressure sensitive mechanical switch. Typically, the switch is operated by pushing the container against, for example, a lever. The lever, in turn, operates the switch that causes the ice and/or water to be dispensed. A number of dispensers employ multiple actuators, one for ice and another for water, while other dispensers employ a single actuator. Dispensers which employ a single actuator typically require additional control elements that enable a user to select between ice and water dispensing operations. Several manufacturers have converted from mechanical switches to electrical or membrane switches. Functioning in a similar manner, a container is pushed against the membrane switch to initiate the dispensing operation. Still other arrangements employ actuator buttons provided on a control panel of the dispenser. With this arrangement, the user continuously depresses a button to release ice and/or water into the container. In yet another arrangement, ultrasonic sensors are mounted in the dispenser well and function to sense a presence and size of the container. The dispenser automatically begins dispensing ice or water based on the presence of the container and stops dispensing before the container overfills.
Over time, mechanical and membrane switches wear out. Physical interaction with the switches results in wear and tear on contact points, springs, levers and the like which eventually require replacement. In addition, buttons, switches and sensors not only add to the overall cost and complexity of the system, but often poses an attraction to young children. Ever curious, young children will often play with the dispenser controls and release water and/or ice onto kitchen floors. In order to address this problem, several manufactures provide their dispensers with a “Lock-Out” feature which, when active, disables operation of the dispenser. While effective, consumers often don't want to turn the system on and off as needed. As such, users do not routinely avail themselves of this option.
Another drawback with existing systems is the lack of an automatic cut-off feature. More specifically, once activated, the dispenser will discharge water or ice until the pressure is removed from the actuator. If the user is momentarily distracted or if the dispenser is operated by an inexperienced individual such as a child, the level of ice or water can overflow the container. There also exist drawbacks with the systems that employ automatic actuators. Most active sensors cannot differentiate between a container and a child's hand. Thus, in such systems, the mere act of a child inserting a hand or other object into the dispenser well will initiate a dispensing operation. In addition, active sensors require both the sending and receiving of signals. Sensors of this type may require periodic alignment and necessitate the use of multiple components which further adds to the overall cost and complexity of the appliance.
Therefore, despite the existence of refrigerator dispensers in the prior art, there still exists a need for an enhanced refrigerator dispensing system. More specifically, there exists a need for a refrigerator dispensing system that employs passive-type sensors, such as capacitive sensors, which do not require contact by a container or other device to initiate a dispensing operation, yet automatically terminate a dispensing operation when a level of ice or water reaches an upper rim of the container. In addition, there exists a need for a refrigerator dispensing system which automatically differentiates between animate and inanimate objects to prevent inadvertent dispensing operations.